Die for extruding honeycomb structural bodies

Abstract

An extrusion die for extruding ceramic honeycomb structural bodies includes body discharge channels having a desired honeycomb arrangement and independent body supply holes communicating with the body discharge channels. The body supply holes are so designed that each of them has inner peripheral surface zones of different inner dimensions and the inner peripheral surface zones may be coaxially arranged.

What is claimed is: 
     
       1. An extrusion die for forming ceramic honeycomb structural bodies from a mass of ceramic material, comprising: an extrusion die body having an entrance surface and an exit surface, said surfaces being located on opposite parallel sides of said die body;   discharge channels formed in said exit surface, said channels being defined by a plurality of intersecting slits which form a matrix corresponding to the geometrical configuration of the honeycomb structural body to be formed thereby, such that said geometric configuration of said honeycomb structural body is formed solely by said discharge channels; and   a plurality of independent body supply holes formed in said entrance surface and extending into the die body from said entrance surface in a direction substantially normal to said entrance surface and directly communicating with said discharge channels, each of said body supply holes having at least two different, coaxially arranged, inner peripheral surface zones, said plurality of independent body supply holes being the first point at which said mass of ceramic material is separated while entering said extrusion die;   wherein the cross-sectional shapes of the body supply holes in each surface zone are substantially the same, and the cross-sectional dimensions of the body supply holes in axially adjacent surface zones are substantially different.   
     
     
       2. An extrusion die according to claim 1, wherein the cross-sectional dimension of one of the at least two inner peripheral surface zones proximate said exit surface is smaller than the cross-sectional dimension of one of the at least two inner peripheral surface zones proximate said entrance surface. 
     
     
       3. An extrusion die according to claim, 1 wherein the cross-sectional shapes of said body supply holes are round. 
     
     
       4. An extrusion die according to claim 2, wherein the cross-sectional shapes of said body supply holes are round. 
     
     
       5. An extrusion die according to claim 1, wherein the cross-sectional dimensions of the body supply holes vary continuously from said entrance surface towards said exit surface. 
     
     
       6. An extrusion die according to claim 2, wherein the cross-sectional dimensions of the body supply holes vary continuously from said entrance surface towards said exit surface. 
     
     
       7. An extrusion die according to claim 3, wherein the cross-sectional dimensions of the body supply holes vary continuously from said entrance surface towards said exit surface. 
     
     
       8. An extrusion die according to claim 4, wherein the cross-sectional dimensions of the body supply holes vary continuously from said entrance surface towards said exit surface. 
     
     
       9. An extrusion die according to claim 1, wherein the cross-sectional shapes of said body supply holes are polygonal. 
     
     
       10. An extrusion die according to claim 2, wherein the cross-sectional shapes of said body supply holes are polygonal. 
     
     
       11. An extrusion die according to claim 1, wherein the cross-sectional dimensions of adjacent inner peripheral surface zones of the body supply holes are different, and the cross-sectional dimensions of alternate inner peripheral surface zones are substantially the same. 
     
     
       12. An extrusion die according to claim 2, wherein the cross-sectional dimensions of adjacent inner peripheral surface zones of the body supply holes are different, and the cross-sectional dimensions of alternate inner peripheral surface zones are substantially the same. 
     
     
       13. An extrusion die according to claim 3, wherein the cross-sectional dimensions of adjacent inner peripheral surface zones of the body supply holes are different, and the cross-sectional dimensions of alternate inner peripheral surface zones are substantially the same. 
     
     
       14. An extrusion die according to claim 4, wherein the cross-sectional dimensions of adjacent inner peripheral surface zones of the body supply holes are different, and the cross-sectional dimensions of alternate inner peripheral surface zones are substantially the same.